Accelerated kinetics of alkaline hydrogen evolution/oxidation reactions on dispersed ruthenium sites through N and S dual coordination

Efficient,robust and cost-effective electrocatalysts that catalyze hydrogen evolution/oxidation reaction(HER/HOR)in alkaline media are highly demanded.Recently,single-atom catalysts(SACs)have emerged as new promising candidates;however,the rational design of supports and the optimization of coordination environment between supports and metal atoms are challenging.In this work,we successfully fabricate atomically dispersed ruthenium(Ru)species,which are strongly coordinated by N and S dual heteroatoms on holey graphene(RuSA/NSG),as an excellent bifunctional catalyst for HER/HOR.In alkaline media,the developed catalyst exhibits high catalytic performance with a low overpotential of 57.3 mV to drive a current density of 10 mA cm^-1 for HER,and its mass activity is about 5.8 times higher than that of commercial Pt/C and Ru/C catalysts at an overpotential of 100 mV.Similarly,considerable HOR performance of Ru SA/NSG is verified to be superior to Pt/C and Ru/C.Furthermore,X-ray-based spectroscopy measurements and density-functional theory calculations have confirmed that,compared with Ru–N₄,the tailored Ru–N₄–S₂ with nearby S dopants can act as more active centers to greatly accelerate the sluggish HER/HOR kinetics in alkaline media.The present work provides a new atomic-level engineering strategy to modulate catalytic activities of SACs via the coordination design using dual heteroatoms on the carbon support.     

Platelet carbon nanofibers as support of Pt-CoO electrocatalyst for superior hydrogen evolution

Exploration of cost-effective Pt/C catalysts has been a significant issue for electrochemical hydrogen evolution reaction(HER) toward sustainable energy conversion and storage.Herein,we report a fabrication strategy by employing platelet carbon nanofibers(p-CNF) as the support to immobilize Pt-CoO HER electrocatalyst using atomic layer deposition method.The edge-rich p-CNF support is found to act as the anchoring sites of Pt nanoparticles and favorably capture electrons from Pt to yield electron-deficient Pt surfaces for the boosted HER.Additionally,the sequential growth of CoO onto the Pt/p-CNF catalyst elaborately constructs the Pt-CoO interface and facilitates the electron transfer from Pt to CoO,which further enhances the HER activity.These advantages endow the fabricated Pt-CoO/p-CNF catalyst with the superior HER activity,e.g.,a very low overpotential of 26 mV at the current density of 10 mA·cm-2 and a mass activity of 4.42 A·mgPt-1at the overpotential of 30 mV,18.8 times higher than that of the commercial20 wt% Pt/C catalyst.The insights reported here could shed light on for the fabrication of cost-effective Pt-based composite HER catalysts.     

Efficient CO2 electroreduction over N-doped hieratically porous carbon derived from petroleum pitch

Developing of economic and efficient catalysts is critical for the application of electroreduction of carbon dioxide to highly valuable chemicals.Herein,we present a facile method to synthesize N-doped hieratically porous carbon through pyrolysis of petroleum pitch followed by ammonia etching.We found mesopores are favored formation by removing of asphaltene from petroleum pitch during the carbonation process.Simultaneously,ammonia etching can not only increase the pyridinic-N content,but also upgrade the ratio of meso-to micro-pores of carbon materials.Using the N-doped hieratically porous carbon as catalyst for carbon dioxide electroreduction,the Faradaic efficiency of carbon monoxide reaches 83%at-0.9 V vs.the reversible hydrogen electrode(RHE)in 0.1 M KHCO₃.This superior performance is attributed to the synergistic effects of highly pyridinic-N content in conjunction with the hieratically porous architecture,rendering abundant exposed and accessible active sites for electroreduction of CO₂.Our work provides a new strategy for the large-scale preparation of high-performance,low-cost catalysts for CO₂ electroreduction.     

Fabrication of K-promoted iron/carbon nanotubes composite catalysts for the Fischer–Tropsch synthesis of lower olefins

K-promoted iron/carbon nanotubes composite(i.e., Fe K-OX) was prepared by a redox reaction between carbon nanotubes and K_2FeO_4followed by thermal treatments on a purpose as the Fischer–Tropsch catalyst for the direct conversion of syngas to lower olefins. Its catalytic behaviors were compared with those of the other two Fe-IM and Fe K-IM catalysts prepared by impregnation method followed by thermal treatments. The novel Fe K-OX composite catalyst is found to exhibit higher hydrocarbon selectivity,lower olefins selectivity and chain growth probability as well as better stability. The catalyst structureperformance relationship has been established using multiple techniques including XRD, Raman, TEM and EDS elemental mapping. In addition, effects of additional potassium into the Fe K-OX composite catalyst on the FTO performance were also investigated and discussed. Additional potassium promoters further endow the catalysts with higher yield of lower olefins. These results demonstrated that the introduction method of promoters and iron species plays a crucial role in the design and fabrication of highly active,selective and stable iron-based composite catalysts for the FTO reaction.     

Boosting pH-Universal Hydrogen Evolution of Molybdenum Disulfide Particles by Interfacial Engineering

The design of high-efficiency non-noble and earth-abundant electrocatalysts for hydrogen evolution reaction(HER)is highly paramount for water splitting and renewable energy systems.Molybdenum disulfide(MoS₂)with abundant edge sites can be utilized as a promising alternative,but its catalytic activity is greatly related to the pH values,especially in an alkaline environment due to the extremely high energy barriers for water adsorption and dissociation steps.Here we report an exceptionally efficient and stable electrocatalyst to improve the sluggish HER process of layered MoS₂particles in different pH electrolytes,especially in base.The electrocatalyst is constructed by in situ growing selenium-doped MoS₂(Se-MoS₂)nanoparticles on three-dimensional cobalt nickel diselenide(mCo_0.2Ni_0.8Se₂)nanostructured arrays.Due to the large number of active edge sites of Se-MoS₂particles exposed at the surface,robust electrical conductivity and large surface area of mCo_0.2Ni_0.8Se₂support,and strong interfacial interactions between Se-MoS₂and mCo_0.2Ni_0.8Se₂,this hybrid catalyst shows very outstanding catalytic HER properties featured by low overpotentials of 30 and 122 mV at 10 and 100 mA/cm²with good operational stability in base,respectively,which outperforms most of inexpensive catalysts consisting of layered MoS₂,transition metal selenides and sulfides,and it performs as well as noble Pt catalysts.Meanwhile,this electrocatalyst is also very active in neutral and acidic electrolytes,requiring low overpotentials of 93 and 94 mV at 10 mA/cm²,respectively,demonstrating its superb pH universality as a HER electrocatalyst with excellent catalytic durability.This study provides a straightforward strategy to construct an efficient non-noble electrocatalyst for driving the HER kinetics in different electrolytes.     

Covalent Triazine Frameworks-derived N,P Dual-doped Porous Carbons for Highly Efficient Electrochemical Reduction of CO_2

Electroreduction of CO_2 into chemicals is of great importance in the global carbon balance.Although noble-metal based catalysts and single-atom catalysts(SACs) are known to be active for CO_2 electroreduction reaction(CO_2 RR), the high cost of noble-metal and the lack of effective synthesis approaches to prepare SACs have tremendously hindered the application. Non-metal doped carbon materials have attracted great interest because of their reasonable cost, chemical stability and excellent electrical conductivity. Nevertheless, the design and fabrication of highly efficient non-metal doped carbon electrocatalysts for CO_2 RR to meet industry demands still remains a big challenge. Herein, triphenylphosphine@covalent triazine frameworks(CTFs) composites were employed as precursors to fabricate N,P dual-doped porous carbon catalysts PCTF-X-Y(X represents the carbonization temperature, and Y represents the mass ratio of CTF to triphenylphosphine) for CO_2 RR. Due to the high specific surface areas and synergistic effect between N and P, the obtained PCTF-1000-5 exhibited high selectivity for CO production up to 84.3% at –0.7 V versus the reversible hydrogen electrode(vs. RHE) and long-term durability over 16 h, which are better than the reported N,P dual-doped carbon catalysts in aqueous media.This work provides a new way to design and fabricate non-metal catalysts for electrocatalysis.     

Carbon layer-coated ordered mesoporous silica supported Co-based catalysts for higher alcohol synthesis: The role of carbon source

Surface chemical properties of supports have an important influence on active sites and their catalytic behavio r.Here,we fabricated a series of cobalt-based catalysts supported by carbon layer-coated ordered mesoporous silica(OMS) composites for higher alcohol synthesis(HAS).The carbon layers were derived from different sources and uniformly coated on the porous surface of OMS.Combined with the characterization results of carbonized catalysts,it is demonstrated that the carbon layer-coated supports significantly enhanced the metal dispersion and increased the ratio of Co2+ to Co0 sites,which further increased the CO conversion and alcohols selectivity.Moreover,it is found that the catalytic activity changed in line with the amount of defects and surface oxygenic groups of carbon layers,which re sulted from the different carbon sources.The highest space time yield of C2+OH was 27.5 mmol gcat-1h-1)obtained by the catalyst coated with glucose-derived carbon layer.But the carbon source is not the key factor influencing the distribution of Co-Co2+ dual sites and shows little effect on selectivity in HAS.These results may guide for further design of carbon supported catalysts.     

Fischer–Tropsch synthesis over iron catalysts with corncob-derived promoters

A sustainable strategy for Fischer–Tropsch iron catalysts is successfully achieved by embedding of synergistic promoters from a renewable resource, corncob. The iron-based catalysts, named as "corncob-driven"catalysts, are composed of iron species supported on carbon as primary active components and various minerals(K, Mg, Ca, and Si, etc.) as promoters. The corncob-driven catalysts are facilely synthesized by a one-pot hydrothermal treatment under mild conditions. The characterization results indicate that the formation of iron carbides from humboldtine is clearly enhanced and the morphology of catalyst particles tends to be more regular microspheres after adding corncob. It is observed that the optimized corncob-driven catalyst exhibits a higher conversion than without promoters' catalyst in Fischer–Tropsch synthesis(ca. 73% vs. ca. 49%). More importantly, a synergistic effect exists in multiple promoters from corncob that can enhance heavy hydrocarbons selectivity and lower CO_2 selectivity, obviously different from the catalyst with promoters from chemicals. The proposed synthesis route of corncob-driven catalysts provides new strategies for the utilization of renewable resources and elimination of environmental pollutants from chemical promoters.     

Understanding the dehydrogenation mechanism over iron nanoparticles catalysts based on density functional theory

The conversion of chemical feedstock materials into high value-added products accompanied with dehydrogenation is of great value in the chemical industry.However,the catalytic dehydrogenation reaction is inhibited by a limited number of expensive noble metal catalysts and lacks understanding of dehydrogenation mechanism.Here,we report the use of heterogeneous non-noble metal iron nanoparticles(NPs) incorporated mesoporous nitrogen-doped carbon to investigate the dehydrogenation mechanism based on experiment observation and density functional theory(DFT) method.Fe NPs catalyst displays excellent performance in the dehydrogenation of 1,2,3,4-tetrahydroquinoline(THQ)with 100% selectivity and 100% conversion for 10-12 h at room temperature.The calculated adsorption energy implies that THQ prefers to adsorb on Fe NPs as compared with absence of Fe NPs.What is more,the energy barrier of transition state is relatively low,illustrating the dehydrogenation is feasible.This work provides an atomic scale mechanism guidance for the catalytic dehydrogenation reaction and points out the direction for the design of new catalysts.     

Boosting electrocatalytic activity for CO2 reduction on nitrogen-doped carbon catalysts by co-doping with phosphorus

Electrochemical reduction of CO₂(CERR)to value-added chemicals is an attractive strategy for greenhouse gas mitigation,and carbon recycles utilization.Conventional metal catalysts suffered from low durability and sluggish kinetics impede the practical application.On the other hand,doped carbon materials recently demonstrate superior catalytic performance in CERR,which shows the potential to diminish the problems of metal catalysts to some extent.Herein,we present the design and fabrication of nitrogen(N),phosphorus(P)co-doped metal-free carbon materials as an efficient and stable electrocatalyst for reduction of CO₂ to CO,which exhibits an excellent performance with a high faradaic efficiency of 92%(-0.55 V vs.RHE)and up to 24 h stability.A series of characterizations including TEM and XPS verified that nitrogen and phosphorous are successfully incorporated into the carbon matrix.Moreover,the comparisons between co-doping and single doping catalysts reveal that co-doping can significantly increase CERR performance.The improved catalytic activity is attributed to the synergetic effects between nitrogen and phosphorous dopants,which effectively modulate properties of the active site.The density functional theory(DFT)calculations were also performed to understand the synergy effects of dopants.It is revealed that the phosphorous doping can significantly lower the Gibbs free energy of COOH^*formation.Moreover,the introduction of the second dopants phosphorous can reduce the reaction barrier along the reaction path and cause polarization of density of states at the Fermi level.These changes can greatly enhance the activity of the catalysts.From a combined experimental and computational exploration,current work provides valuable insights into the reaction mechanism of CERR on N,P co-doped carbon catalysts,and the influence from synergy effects between dopants,which paves the way for the rational design of novel metal-free catalysts for CO2 electro-reduction.     

Cu/Cu_2O nanoparticles co-regulated carbon catalyst for alkaline Al-air batteries

Developing high-efficiency,inexpensive,and steady non-precious metal oxygen reduction reaction(ORR) catalysts to displace Pt-based catalysts is significant for commercial applications of Al-air battery.Here,we have prepared the Cu/Cu_2 O-NC catalyst with excellent ORR performance and high stability,due to the synergistic effect of Cu and Cu_2 O nanoparticles.The half-wave potential(0.8 V) and the limiting-current density(5.20 mA/cm~2) of the Cu/Cu_2 O-NC are very close to those of the 20% Pt/C catalyst(0.82 V,5.10 mA/cm~2).Besides,it exhibits excellent performance with a maximal power density of 250 mW/cm~2 and a stable continuous discharge for more than 90 h in the Al-air battery test The promoting effects of Cu_2 O towards Cu-based ORR catalysts are illustrated as follows:(ⅰ) Cu_2 O is the major ORR active site by the redox of Cu(Ⅱ)/Cu(Ⅰ),which provides excellent ORR activities;(ⅱ) Cu can stabilize the location of Cu_2 O by assisting the electron transfer to Cu(Ⅱ)/Cu(Ⅰ) redox,which is conducive to the high stability of the catalyst.This work provides a useful strategy for enhancing the ORR performance of Cu-based catalysts.     

Remarkable synergistic effect in cobalt-iron nitride/alloy nanosheets for robust electrochemical water splitting

Design and synthesis of noble-metal-free bifunctional catalysts for efficient and robust electrochemical water splitting are of significant importance in developing clean and renewable energy sources for sustainable energy consumption.Herein,a simple three-step strategy is reported to construct cobalt-iron nitride/alloy nanosheets on nickel foam(CoFe-NA/NF)as a bifunctional catalyst for both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).The electrocatalyst with optimized composition(CoFe-NA2/NF)can achieve ultralow overpotentials of 73 mV and 250 mV for HER and OER,respectively,at a current density of 10 mA cm^-2 in 1 M KOH.Notably,the electrolyzer based on this electrocatalyst is able to boost the overall water splitting with a cell voltage of 1.564 V to deliver 10 mA cm^-2 for at least 50 h without obvious performance decay.Furthermore,our experiment and theoretical calculation demonstrate that the combination of cobalt-iron nitride and alloy can have low hydrogen adsorption energy and facilitate water dissociation during HER.In addition,the surface reconstruction introduces metal oxyhydroxides to optimize the OER process.Our work may pave a new pathway to design bifunctional catalysts for overall water splitting.     

Hydrogen evolution kinetics on Ni cathodes modified by spontaneous deposition of Ag or Cu

Nickel modification by spontaneous deposition of transition metals such as Ag and Cu is shown as an economic and simple alternative for the activation of hydrogen evolution reaction(HER) on cathodes in alkaline media. The kinetics of HER is studied on Ni/Ag and Ni/Cu catalysts by cyclic voltammetry and electrochemical impedance spectroscopy(EIS) using a rotating disk electrode(RDE). Freshly synthesized catalysts, as well as catalysts subjected to a short chronoamperometric ageing procedure, are analyzed and the kinetic and thermodynamic parameters of the HER are obtained. The nickel surface modified with transition metals with an outer shell electronic configuration [xd~(10)(x+1)s~1], such as Cu(3d~(10)4s~1)and Ag(4d~(10)5s~1), shows an improved activity for the HER compared to bare nickel. Furthermore, the Ni/Cu catalyst presents a decreased onset potential. The hydrogen evolution rate, measured as current density at –1.5 V(vs. SCE), is similar on Ni/Cu and Ni/Ag electrodes.     

Biomass-derived bifunctional electrocatalysts for oxygen reduction and evolution reaction: A review

Oxygen electrode catalysts are important as inter-conversion of O₂ and H₂O is crucial for energy technologies.However,the sluggish kinetics of oxygen reduction and evolution reactions(ORR and OER)are a hindrance to their scalable production,whereas scarce and costly Pt and Ir/Ru-based catalysts with the highest electrocatalytic activity are commercially unviable.Since good ORR catalysts are not always efficient for OER and vice versa,so bifunctional catalysts on which OER and ORR occurs on the same electrode are very desirable.Alternative catalysts based on heteroatom-doped carbon nanomaterials,though showed good electrocatalytic activity yet their high cost and complex synthesis is not viable for scalable production.To overcome these drawbacks,biomass-derived heteroatom-doped porous carbons have recently emerged as low-cost,earth-abundant,renewable and sustainable environment-friendly materials for bifunctional oxygen catalysts.The tunable morphology,mesoporous structure and high concentration of catalytic active sites of these materials due to heteroatom(N)-doping could further enhance their ORR and OER activity,along with tolerance to methanol crossover and good durability.Thus,biomassderived heteroatom-doped porous carbons with large surface area,rich edge defects,numerous micropores and thin 2 D nanoarchitecture could be suitable as efficient bifunctional oxygen catalysts.In the present article,synthesis,N-doping,ORR/OER mechanism and electrocatalytic performance of biomassderived bifunctional catalysts has been discussed.The selected biomass(chitin,eggs,euonymus japonicas,tobacco,lysine and plant residue)except wood,act as both C and N precursor,resulting in N selfdoping of porous carbons that avoids the use of toxic chemicals,thus making the synthesis a facile and environment-friendly green process.The synthetic strategy could be further optimized to develop future biomass-based N self-doped porous carbons as metal-free high performance bifunctional oxygen catalysts for commercial energy applications.Recent advances and the importance of biomass-based bifunctional oxygen catalysts in metal-air batteries and fuel cells has been highlighted.The material design,perspectives and future directions in this field are also provided.     

Enhanced confinement synthesis of atomically dispersed Fe-N-C catalyst from resin polymer for oxygen reduction

Due to larger atom utilization,unique electronic properties and unsaturated coordination,atomically dispersed non-precious metal catalysts with outstanding performances have received great attention in electrocatalysis.Considering the challenge of serious aggregation,rational synthesis of an atomic catalyst with good dispersion of atoms is paramount to the development of these catalysts.Herein,we report an enhanced confinement strategy to synthesize a catalyst comprised of atomically dispersed Fe supported on porous nitrogen-doped graphitic carbon from the novel and more cross-linkable Melamine-Glyoxal Resin.Densified isolated grid trapping,excessive melamine restricting,and nitrogen anchoring are strongly combined to ensure the final atomic-level dispersion of metal atoms.Experimental studies revealed enhanced kinetics of the obtained catalyst towards oxygen reduction reaction(ORR).This catalytic activity originates from the highly active surface with atomically dispersed iron sites as well as the multi-level three-dimensional structure with fast mass and electron transfer.The enhanced confinement strategy endows the resin-derived atomic catalyst with a great prospect to develop for commercialization in future.     

Red-blood-cell like nitrogen-doped carbons with highly catalytic activity towards oxygen reduction reaction

A highly active nitrogen-doped catalyst with a unique red-blood-cell(RBC) like structure is reported for oxygen reduction reaction(ORR).The catalyst Fe,N-C@carbon-900 was prepared by pyrolysis of the polyaniline(PANl) and polystyrene(PS) composites with adsorption of ferric ion on the shell of sphere structure at 900℃.Fe,N-C@carbon-900 with a unique RBC-like structure provides plenty of catalytic sites combining the electrical conductivity of the carbon sphere with the catalytic activity of the nitrogen-doped layer.The four-electron reduction pathway is selected for the catalyst Fe,N-C@carbon-900.The catalyst exhibit the ORR E_(onset) at 0.87 V(potentials is versus to reversible hydrogen electrode(RHE)),E_(1/2) at 0.78 V and high diffusion-limiting current density(5.20mA/cm~2).Furthermore,this work indicates that both N and Fe accounted for high activity of the catalyst Fe,N-C@carbon-900 toward the oxygen reduction process.It is concluded that Fe and N exhibit synergistically promotion in the ORR activity for the catalyst Fe,N-C@carbon-900.We also provide a rational design of electrocatalysts with high ORR activity to further clarify the essential ORR sites of heteroatom doped carbon materials for fuel cells and metal-air battery applications.     

Carbon hybrid with 3D nano-forest architecture in-situ catalytically constructed by CoFe alloy as advanced multifunctional electrocatalysts for Zn-air batteries-driven water splitting

Rational design and facile synthesis of non-noble materials as the effective multifunctional electrocatalysts are still challenging. Herein, a self-catalytically grafted growth approach is developed to construct carbon hybrid with three-dimensional(3 D) nano-forest architecture via controlled pyrolysis of metalpolymer nanofiber precursor and melamine. The metal-polymer nanofibers act as the matrix, and melamine is used as the initiator for orientated growth of one-dimensional(1 D) N-doped carbon nanotubes(N-CNTs) on carbon nanofibers. The as-prepared CoFe-N-CNTs/CNFs-900 possesses unique structure and component advantages in terms of 3 D structure, special synapse-like structure, porous feature,high-level N doping and bimetallic active components, which endow the material with structural stability, high mass/electron transport ability and large active sur-/interfaces. Benefiting from the integrated effects of all the above factors, CoFe-N-CNTs/CNFs were successfully applied to overall water splitting and Zn-air batteries. It is believed that this integrated design methodology can be extended to prepare other MàNàC materials for energy-related electrochemical reactions.     

Self-supported Ni2P nanosheets on low-cost three-dimensional Fe foam as a novel electrocatalyst for efficient water oxidation

Electrochemical water splitting into hydrogen and oxygen is a promising strategy for future renewable energy conversion devices.The oxygen evolution reaction(OER)is considered as the bottleneck reaction in an overall water splitting system because it involves 4e~- and 4H~+ transfer processes.Currently,it is highly desirable to explore low-cost alternative catalysts for OER at ambient conditions.Herein,we report for the first time that nickel phosphide(Ni_2P)nanosheets can be facilely grown on Fe foam(FF)as an efficient electrocatalyst for OER with excellent durability and catalytic activity under alkaline conditions.To reach a current density of 10 m A/cm~2,the Ni_2P-FF catalyst required a low overpotential of only 198 mV for OER.The catalyst’s high OER activity and durability were well maintained at a high current density.The required overpotentials were only 267 and 313 mV to achieve the current densities of 100 and 300 m A/cm~2,respectively.The combination of low-cost Fe foam with Ni_2P provides a promising low-cost catalyst for large-scale application of electrocatalytic water splitting.     

P-Ni4Mo Catalyst for Seawater Electrolysis with High Current Density and Durability

Rational design of highly efficient and durable electrocatalysts with low cost to replace noblemetal based catalysts for seawater electrolysis is extremely desirable, but challenging. In this work, we demonstrate a rapid electrodeposition method by growing P-Ni₄Mo on the surface of the copper foam（CF）substrate to synthesize an efficient seawater electrolysis catalyst（P-Ni₄Mo/CF）. The catalyst exhibited considerable HER performance and stability in alkaline seawater, with th...     

In situ construction of Co/N/C-based heterojunction on biomass-derived hierarchical porous carbon with stable active sites using a Co-N protective strategy for high-efficiency ORR,OER and HER trifunctional electrocatalysts

The facile designs and fabrication of noble metal-free electrocatalysts are highly required to achieve multifunctional catalytic activity with excellent stability in Zn-air batteries,fuel cells and water splitting systems.Herein,a heterostructure engineering is applied to construct the high performance Co,Ncontaining carbon-based multifunctional electrocatalysts with the feature of isotype(i.e.n-n type Co₂N_0.67-BHPC)and anisotype(i.e.p-n type Co₂O₃-BHPC)heterojunctions for ORR,OER and HER.The nn type Co₂N_0.67-BHPC,in which biomass(e.g.mushroom)-derived hierarchical porous carbon(BHPC)incorporated with nonstoichiometric active species Co₂N_0.67,is fabricated by using an in situ protective strategy of macrocyclic central Co-N₄ from CoTPP(5,10,15,20-tetrakis(phenyl)porphyrinato cobalt)precursor through the intermolecularπ-πinteractions between CoTPP and its metal-free analogue H₂ TPP.Meanwhile,an unprotected strategy of macrocyclic central Co-N₄ from CoTPP can afford the anisotype Co₂O₃-BHPC p-n heterojunction.The as-prepared n-n type Co₂N_0.67-BHPC heterojunction exhibited a higher density of Co-based active sites with outstanding stability and more efficient charge transfer at the isotype heterojunction interface in comparison with p-n type Co₂O₃-BHPC heterojunction.Consequently,for ORR,Co₂N_0.67-BHPC exhibits the more positive onset and half-wave potentials of 0.93 and 0.86 V vs.RHE,respectively,superior to those of the commercial 20 wt%Pt/C and most of Cobased catalysts reported so far.To drive a current density of 10 mA cm^-2,Co₂N_0.67-BHPC also shows the lower overpotentials of 0.34 and 0.21 V vs.RHE for OER and HER,respectively.Furthermore,the Zn-air battery equipped with Co₂N_0.67-BHPC displays higher maximum power density(109 mW cm^-2)and charge-discharge cycle stability.Interestingly,the anisotype heterojunction Co₂O₃-BHPC as trifunctional electrocatalyst reveals evidently photoelectrochemical enhancement compared with the photostable Co₂N_0.67-BHPC.That is to say,isotype heterojunction material(n-n type Co²N_0.67-BHPC)is equipped with better electrocatalytic performance than anisotype one(p-n type Co₂O₃-BHPC),but the opposite is true in photoelectrochemical catalysis.Meanwhile,the possible mechanism is proposed based on the energy band structures of the Co₂N_0.67-BHPC and Co₂O₃-BHPC and the cocatalyst effects.The present work provides much more possibilities to tune the electrocatalytic and photoelectrochemical properties of catalysts through a facile combination of heterostructure engineering protocol and macrocyclic central metal protective strategy.